1. Field of the Invention
The present invention relates to a photoelectric conversion device and a camera system.
2. Description of the Related Art
A conventional phase difference detection type focus detection apparatus calculates the defocus amount of an object by computing correlation of photoelectric conversion signals from a pair of line sensors, thereby performing auto focus. According to Japanese Patent Laid-Open No. 2006-220684, when providing a plurality of focus detection areas, the apparatus includes a plurality of accumulation control areas. In this case, sensor units configured for the respective areas are accompanied by storage units. The apparatus disclosed in Japanese Patent Laid-Open No. 2006-220684 includes two storage units accompanying the sensor unit to shorten the time required for focus detection in the case of a large defocus. For a general defocus, the apparatus performs correlation computation of the accumulated signal stored in the first storage unit. For a large defocus, the apparatus performs correlation computation of the accumulated signal stored in the second storage unit.
Japanese Patent Laid-Open No. 2002-77737 discloses a technique of increasing the dynamic range of an image sensor by providing intra-pixel capacitors and performing two kinds of exposures which differ in their exposure end times. At the end of the first exposure, the apparatus transfers the photocharge accumulated in each photodiode to a corresponding intra-pixel capacitor, and reads out a mixture of the photocharge accumulated in the photodiode and the charge in the intra-pixel capacitor at the end of the next exposure.
In addition, Japanese Patent Laid-Open No. 9-200614 discloses a reset noise reduction unit which improves the S/N ratio of a photoelectric conversion signal read out from a sensor.